1. Field of the Invention
The disclosures discussed herein generally relate to an ink-jet head and an ink-jet recording apparatus.
2. Description of the Related Art
The applied micro-electromechanical system (MEMS) technology is known in the art as a technology to densify the ink-jet head (a drop-wise ink-jet head) utilizing a piezoelectric element. Such an ink-jet head may be formed in an actuator structure composed of a piezoelectric element, which is formed by patterning an individual electrode, a common electrode and a piezoelectric body formed on a vibrating plate.
However, the piezoelectric element generally has an electric property that deteriorates due to moisture in the atmosphere. Japanese Patent Application Publication No. 2010-42683 (hereinafter referred to as “Patent Document 1”) discloses an ink-jet head having a configuration in which layers forming the piezoelectric element and a pattern region of a lead electrode for an upper electrode are covered with an insulator film formed of an inorganic amorphous material in order to overcome the deterioration of the electric property of the piezoelectric element due to the moisture in the atmosphere. In the ink-jet head disclosed in Patent Document 1, the insulator film includes a first insulator film and a second insulator film, and the piezoelectric element is covered with the first insulator film excluding a connecting portion connected to the lead electrode for the upper electrode. Further, the lead electrode of the upper electrode extends over the first insulator film, and the layers forming the piezoelectric element and the pattern region of the lead electrode for the upper electrode are covered with the second insulator film excluding a region facing a connecting portion connected to a connecting wire.
However, in the ink-jet head disclosed in Patent Document 1, the entire pattern region including the piezoelectric element is covered with the insulator film. Accordingly, the displacement of the piezoelectric element may be significantly inhibited if the piezoelectric element is covered with the thick insulator film. On the other hand, if the piezoelectric element is covered with the thin insulator film, a withstanding voltage between the lead electrode and a lower electrode may not be secured. Thus, it may be necessary to arrange the electrodes such that the lead electrode is not overlapped with the lower electrode. However, with this configuration, the ink-jet head may not be significantly reduced in size or components of the ink-jet head may not be significantly densified.